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10-24-2009, 03:04 AM   #16
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QuoteOriginally posted by pacerr Quote
but I've read more than one presumably knowledgeable person that noted that the 50-55mm focal length is the easiest FL to design and manufacture a fast lens for in the 135 format.
As the registration distance for most cameras is between 40-46mm, a 50mm focal length is about the shortest you can produce in a simple symetric lens design. Much shorter than this and the focal length is shorter than the registration distance and this required a non symetric retrofocus lens design (like a reversed telephoto). Keeping a lens design symetric makes it a lot easire to correct off axis aberations and distortion. The added complexity of making a retrofocus lens is the reason there was little available bellow 40mm in the early days of SLR's. Longer focal lengths can also be mady with a symetric design but they tend to get large and heavy so non symetric telephoto designs are usually employed.

10-24-2009, 03:46 AM   #17
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QuoteOriginally posted by vandamro Quote
What hood do you use for FA 50 1.4? I've been looking all over the place for one!
Best one IMO is a collapsible rubber one - available in many places, esp. eBay. Cheap and allows easy access to the lens cap.
10-24-2009, 04:36 AM   #18
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Generally speaking a manual focus 50mm lens is the cheapest way to have fun at f/1.4.

Of course I don't take into account the well known expensive lenses out there like Voigtlander and Zeiss or other "boutique" lenses like SMC Pentax 50mm f/1.2, Leica R Summilux 50mm f/1.4 RE Auto Topcor 58mm f/1.4, Nikkor Noct 58mm f/1.2 or the Minolta Rokkor 58mm f/1.2.

But the Takumar 50mm f/1.4 is a great lens at a very reasonable price.

Last edited by Voe; 10-24-2009 at 04:46 AM.
10-24-2009, 04:46 AM   #19
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I just saw new Nikon 50/1.8 and Canon 50/1.4 for about $150 (Australian) for sale in a shop today. I wish Pentax lenses were even half that cheap!

10-24-2009, 08:40 AM   #20
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QuoteOriginally posted by WheresWaldo Quote
While everyone else doles out praises for the 50mm, and I have one too. It is a real odd focal length for me, just a bit too long for tight shots and a bit too short for telephoto.
Right, and this is something that should be made clear to the OP: most of the comments about the advantages of 50mm lenses are not really about 50mm lenses specifically - they are about primes (single focal length lenses, as opposed to zooms) in general. It just happens that 50mm tends to be the cheapest prime you can get - often on the order of $20-$50 used (for manual focus).

But I agree, it isn't my favorite focal length. I've got eight primes, with a ninth on the way, and the 50 is the least used of these. But a 50 was also my first prime - specifically because it was so cheap - and they are often among the fastest (large maximum aperture = fast shutter speed) and sharpest lenses you'll ever use.
10-24-2009, 08:48 AM   #21
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QuoteOriginally posted by Spock Quote
I just saw new Nikon 50/1.8 and Canon 50/1.4 for about $150 (Australian) for sale in a shop today. I wish Pentax lenses were even half that cheap!
I suspect you mean the Canon 50/1.8. The Canon 50/1.4 is usually more expensive than the Pentax 50/1.4. The new Nikon 50/1.4 is more expensive still, although now that it is available, the price of their older 50/1.4 has dropped to the point where it can be a bit cheaper than Pentax's.

Anyhow, the point being, it's important to compare apples to apples here - if you compare 50/1.4's rather than mixing and matching 1.4's and 1.8's, the price difference you are seeing disappears or even reverses itself, even after the recent price increases on the Pentax side. Of course, I certainly I agree it would be great if Pentax offered a cheap 50/1.7, although I think it would be far better for them to concentrate on getting the 35/2 back out, since that's the more generally useful focal length on APS-C.
10-24-2009, 09:18 AM   #22
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It's about being normal

50mm is called a "normal lens". Most people think this means that it gives the same field of view as the human eye. That's not so. It gives the same *angle* of view. The difference is about compressing or separating objects in your photos.

Shorter focal lengths separate objects. That is, things look farther apart. Longer focal lengths compress objects. 50mm is the "baby bear-just right" match for human vision.

Even with APS sensor cameras, 50mm still gives the same lack of subject compression or widening. The 1.5 magnification factor on the sensor is a crop factor, which gives apparent magnification. It doesn't affect the optical qualities of the lens. Knowing about object separation/compression gives more creative control over your photos.

Yes, there are the advantages of sharpness and speed with a prime lens, but those are not confined to the 50mm focal length. You get the other advantage of 50mm even with a zoom.

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10-24-2009, 09:38 AM   #23
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No appeal here. For me, the crop factor relegates my manual 50mm to the shelf. I would rather use my Tamron 28mm as a small lens.

I think the 50mm's are popular and have staying power because they give you a inexpensive, good IQ, and fast prime since they were originally designed to be the lenses sold with film bodies. No longer inexpensive for Pentax, it appears.

I am surprised that the Pentax 50mm AF has gone up to $360. When I first bought a K100D back in 2006, I recall they were going for around $200-250. But maybe my memory is bad.


Last edited by chedoy; 10-24-2009 at 11:29 AM.
10-24-2009, 10:29 AM   #24
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QuoteOriginally posted by mysticcowboy Quote
50mm is called a "normal lens". Most people think this means that it gives the same field of view as the human eye. That's not so. It gives the same *angle* of view. The difference is about compressing or separating objects in your photos.

Shorter focal lengths separate objects. That is, things look farther apart. Longer focal lengths compress objects. 50mm is the "baby bear-just right" match for human vision.

Even with APS sensor cameras, 50mm still gives the same lack of subject compression or widening. The 1.5 magnification factor on the sensor is a crop factor, which gives apparent magnification. It doesn't affect the optical qualities of the lens.
This gets discussed repeatedly in different contexts, including a couple of threads going on (well, mostly just winding down) right now. Search the forums for recent threads involving the terms "perspective" and "normal". See, for instance, this one:

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/77171-whats-more-normal.html

Suffice it to say that the statements above include some commonly held perceptions that have basis in truth, but there are some inaccuracies there too.

For one thing, the 50mm focal length does *not* correspond to the angle of view of human vision - our vision is *much* wider than that. That was already true of 50mm on FF, but it's even more true on APS-C. It's easy enough to see - look across the room, gauge how much of the room you can see (leftmost and rightmost objects you can simultaneously see) , then stick a camera with a zoom lens up to your face and zoom until the view matches. My 18-55 doesn't go wide enough to encompass everything I can see - peripheral vision is *huge*.

At some kind of vague subjective level, though, it *is* true the angle of view of a 50mm lens on FF does sort of correspond to the part of what we see that we can "focus" in some sense. But this too changes drastically because of the crop factor - we are *not* taking about optical qualities of the lens (which indeed don't change), but simple angle of view (which does).

The sense in which 50mm was actually "normal" for FF has to do with what is called "perspective distortion", which is what you are alluding to in talking about compressing or widening apparent distances. But again, this is not an optical quality of the lens (which doesn't change because of the crop factor), but rather a simple function of ngle of view (which is exactly what the crop factor changes). So a 50mm lens on APS-C *does* have a slight compression factor to it in this sense - the same as a 75mm lens on FF. It's 33mm on APS-C that would provide the same angle of view - and hence the same lack of perspective distortion - as 50mm on FF. And actually, both those numbers are slightly on the long side; the most neutral focal length for FF is usually taken to be 43mm, not 50mm. And hence the most "normal" lens on APS-C is actually a 28mm lens.
10-24-2009, 11:10 AM   #25
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QuoteOriginally posted by pacerr Quote
This may be a chicken-and-egg argument, and I'll not repeat the often voiced point about 50mm being the normal FOV for normal people at a normal viewing distance, but I've read more than one presumably knowledgeable person that noted that the 50-55mm focal length is the easiest FL to design and manufacture a fast lens for in the 135 format.

I haven't seen proof of that, but the preponderance of excellent, low(er) cost 50's in all brands would seem to support that view.

Could just be 'cause 50mm is normal, but I'd think there'd be some strong marketing ploys if there was an alternative FL.

H2
Well, sorta.

43mm's normal on a 35mm cameras (it's why the FA 43 is what it is.) 45mm would be much more logical, I suppose.

Thing is, it's actually a bit easy to design telephotos, especially with SLRs. A lot of telephoto primes have less elements than 50mm, and are still of comparable quality.

Back when the 35mm camera system kicked off with Ur-Leica, the bloke who designed it, Oskar Barnack, decided on a 50mm lens as a standard, although they weren't thought of as "standard" back then. Why? Who knows. It became standard, after a while. Although I haven't looked into, Barnack probably got the lens formula from Zeiss, who're responsible for a shedload of optical innovation - Tessar, Sonnar, Planar for starters, which were widely copied, with good reason. Most fifties are based on the Zeiss Planar - a design dating from 1896 - including Pentax's.

Basically, manufacturers started...not quite copying, but certainly using the principles Barnack had developed, and it was just easier, and anyway 50mm on 35mm film's a pretty good length.

So, 50mm lenses are what lensmakers got good at. The kinks got worked out early (the FA 1.4 50mm is optically identical to the 1976 K 1.4 50mm - in fact, none of the later Pentax fifties differ from their earlier counterparts, save for number of aperture blades.) They're small, and their perspective makes it easier for people to compose a shot, as looking through the viewfinder with a 50-odd millimetre lens on it doesn't shock you with a whole bunch of extra stuff outside of your main field of view.

You don't need a lot of glass to make 'em fast, either. An f1.4 50mm needs only a slightly curved front element 35mm in diameter.

Now, since, back in the day, since this was a standard lens everyone expected a camera to have, the fifties were the kit lenses. Every camera came with one (you could probably pick between a cheaper, slower one, or a more expensive, faster one. I wasn't there.)

That's why they tend to be cheap, yet well done. They're easy to make, because all the research and design has been done, and more importantly, has been pretty much perfected. There're a lot of them, keeping down the price, because they were a nice practical focal length and sold with pretty much every camera up until the eighties.

As for whether it's a good standard lens, that's a matter of choice. Some swear by 40mm, some by 35mm. The term "standard" or "normal" really only applies to the "standard" lens you "normally" shoot with.
10-24-2009, 12:50 PM   #26
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QuoteOriginally posted by lithos Quote
the FA 1.4 50mm is optically identical to the 1976 K 1.4 50mm - in fact, none of the later Pentax fifties differ from their earlier counterparts, save for number of aperture blades.
My K f/1.4 is 52mm filter size while the m, a, f, and fa are all 49mm. I don't see how they can be the same optically
10-24-2009, 03:00 PM   #27
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QuoteOriginally posted by vandamro Quote
What hood do you use for FA 50 1.4? I've been looking all over the place for one!
Adorama has all kinds. I use a metal round one.
10-24-2009, 03:36 PM   #28
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50mm has a long heritage in the FF world. As others have mentioned it is was considered a 'normal' lens in that it gives the image you see through the lens and the human eye at a similar magnification.

This was generally also the 'standard' kit lens that would be provided with most manual cameras for people to start learning on, forcing them to work on composition and concentrating on technique. Essentially, the lens was a fixed parameter except for focus. The rest came from understanding how the shutter and aperture affects the final image output.

Indeed I find it is a nice approach to take. When someone asks me for some general instruction on SLR photography - I'm inclined to hand them one of my bodies with an old manual focus prime lens on it to make use of the distance markers to help explain things.

Having said that, there are two things that don't translate quite the same in the APS-C world that people seem to cling on to the ideal of the 50mm lens to.

1. It is no longer a 'normal' lens due to the 1.5x crop factor - so really one would look for something closer to the 30-35 mm range.

2. the smaller sensor inherently gives a greater depth of focus by about one stop, so really an equivalent to the 50 1.4 in the APS-C world would have to be closer to a 35 mm 1.2 to give the same control over depth-of-field. No doubt many photographers would lust for a lens like that today if not for how large and heavy it would be.

Next time you're out at a camera store, bring and memory card and ask to handle an FF with a 50 1.4 to play around with in the store and you'll get a good sense of why it was so revered as a creative tool.
10-24-2009, 05:43 PM   #29
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I think the reason why so many people like the 50 is because it is the cheapest way to get really wide apertures. Old SLRs often came with a 50 mm lens for the above reasons. It was a cheap lens to make and there are tons of them out there for varying prices, depending on whether or not you need auto metering and auto focus.

That said, it is not a good focal length for me. I would far rather have the DA 40 and 70 in my bag than the FA 50. It just feels too short half of the time and too long the other half, but that's probably just me...
10-24-2009, 07:02 PM   #30
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50mm was a very useful focal length on film for general photography. It was a one lens solution for most needs. The idea was you started with a 50mm and then added a wide angle and/or a telephoto later once you knew what you needed to take your photography forward.

I used a 50mm for years as my sole lens and found it amazingly versatile. I only occasionally found it a bit restrictive with indoor group shots and landscapes that demanded a wide angle.

On digital, I find 50mm too long for general photography so I sold my 50mm when I realised I wasn't using it any more.

I did miss having a fast prime standard lens and thus recently bought a 28mm prime to fulfill the same role on my digital - and I am loving it!
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